FIELD OF THE INVENTION
The invention relates to a method for starting a multicylinder internal combustion engine.
In a heretofore known manner, the working cycle of an internal combustion engine is made up of the work strokes of intake, compression, working and expulsion. On intake, the inlet valve is opened, while on expulsion the outlet valve is opened. In a multicylinder internal combustion engine with at least four cylinders, at least, respectively, two pistons at a time are simultaneously at top dead center, namely at the beginning of the intake stroke and at the beginning of the work stroke, respectively, in which the combustion takes place by ignition or fuel injection. The opening and closing of the inlet valves and outlet valves is effected either with a conventional camshaft controller or with solenoid valves triggered by an engine control unit.
From the published European Patent Document EP 0 367 443 A1, a valve controller for an internal combustion engine having inlet valves and outlet valves which are operated electromagnetically has become known heretofore. The valve controller turns one or more cylinders off in ongoing succession in the overrunning mode, by keeping both the inlet valve and the outlet valve closed, so that the cylinder compresses and expands without air or fuel being supplied.
The published German Patent Document DE 32 29 691 A1 describes a starter device for a multicylinder internal combustion engine which is intended to render superfluous a starter operated by an electric motor. In the underlying internal combustion engine, the valve control is effected mechanically. The inlet valves have an overpressure function, as a result of which, at a given overpressure in the cylinder, the inlet valves close even in the open state thereof. The outlet valves function conventionally. By means of a compressor driven by an electric motor and by means of the inlet valves with the overpressure function, when the stopped engine is started, ignition takes place simultaneously in two cylinders at a single time. The cylinders which are involved are specifically the cylinder that would be in the combustion stroke when the engine is running, and the cylinder having a piston that is in some setting of the intake stroke. In the latter cylinder, compressed air is passed through the opened inlet valve and fuel is injected, and this air and fuel mixture which is at overpressure is ignited. This causes a further pressure rise in this cylinder, the inlet valve of which is open. Because of the increased overpressure, the inlet valve closes due to the overpressure function thereof, and the piston of this cylinder follows along with the expansion motion. The other cylinder in which ignition occurs is in a setting of the combustion stroke and, therefore, the valves thereof are closed, and ignition can occur in a conventional manner. A result thereof is that an internal combustion engine is set into motion without a starter operated by an electric motor. Thereafter, engine operation takes place in the normal ignition order and the normal order of working strokes, respectively, which, because of the conventional outlet valves with mechanical control cannot, in any event, be otherwise possible.